Dock levelers are commonly used in loading docks of commercial and industrial buildings to match a level of the floor of the loading dock of the building with a bed or floor of the vehicle to permit personnel to easily move goods or equipment to load and unload the vehicle (e.g. via forklifts). Typically a dock leveler includes a metal deck plate and a mechanism for adjusting the height and possibly also the slope of the metal deck plate to compensate for a height difference between a level of the bed or floor of the vehicle and a level of the loading dock floor. Often a dock leveler also includes an extension plate or lip that extends to span a gap between the edge of the loading dock and an edge of the bed or floor of the vehicle. The mechanism for adjusting the height and slope of the metal deck plate is usually disposed in a pit in the floor of the loading dock. This pit has an opening in the loading dock floor that is larger than the metal deck plate. During periods of time that the dock leveler is not being used, the metal deck plate is in a position that is level with the floor of the loading dock. In this position, there are gaps between the edges of the metal deck plate of the dock leveler and the floor of the loading dock due to the pit opening being larger than the metal deck plate. The pit in which the dock leveler is disposed often has an opening on an outward facing side of the loading dock as well as an opening in the loading dock floor, which exposes the pit to environmental conditions and contaminants outside the loading dock even when the loading dock door is fully lowered. This can lead to substantial heat transfer from outside the loading dock to inside the building or vice versa due to air flow through the pit and the gaps, and due to thermal conduction through the metal deck plate of the dock leveler even when the loading dock door is fully closed. Further, contaminants can enter the building through the gap, especially during windy conditions.